Changed minimum deployment target to iOS 6.0

• Changed minimum deployment target from iOS 5.0 to iOS 6.0 in project and PKRevealController settings in order to fix build ability.
	» The NS_ENUM() and NS_OPTIONS() macros used all over were introduced in iOS 6.0's Foundation.  With a minimum deployment target of iOS 5.0, the build fails.

This fixes issue #160.